FIG. 1 is a plane view of a related-art piezoelectric actuator. FIG. 2 is a cross-sectional view of the piezoelectric actuator along a line X-X in FIG. 1.
With reference to FIGS. 1 and 2, the related-art piezoelectric actuator 200 includes a support member 201; pads 203-205; a common lower electrode 206; a first piezoelectric actuator 207; a second piezoelectric actuator 208; and a wiring 209.
The support member 201 includes a thick support part 211 and a support body 212 which is formed integrally with the support part 211 and is thinner than the support part 211. The support body 212 has an L-shape and is supported by the support part 211.
The support body 212 includes a first support part Z1 on which the first piezoelectric actuator 207 and the wiring 209 are formed, and a second support part Z2 on which the second piezoelectric actuator 208 is formed. The first support part Z1 is disposed between the support part 211 and the second support part Z2. The first support part Z1 includes an area in which the first piezoelectric actuator 207 is formed and an area in which the wiring 209 is formed.
The pads 203-205 are provided on an upper surface 211A of the support part 211. The pads 203 and 204 are provided for applying voltage to the first piezoelectric actuator 207. The pads 204 and 205 are provided for applying voltage to the second piezoelectric actuator 208.
The common lower electrode 206 is provided on an upper surface 212A of the support body 212. The common lower electrode 206 is electrically coupled to the pad 203.
The first piezoelectric actuator 207 is provided on an upper surface of the first support part Z1. The first piezoelectric actuator 207 includes a piezoelectric body 215; a part of the common lower electrode 206 which is located below the piezoelectric body 215; and an upper electrode 216 provided on the piezoelectric body 215.
The upper electrode 216 is electrically coupled to the pad 204. When the voltage is applied to the first piezoelectric actuator 207, the piezoelectric body 215 displaces in a first direction (specifically, a contraction direction or an expansion direction) to deform and bend the first support part Z1.
The second piezoelectric actuator 208 is provided on an upper surface of the second support part Z2. The second piezoelectric actuator 208 includes a piezoelectric body (not illustrated) formed from a piezoelectric material as is the case with the piezoelectric body 215; a part of the common lower electrode 206 which is located below the relevant piezoelectric body; and an upper electrode 218 provided on the relevant piezoelectric body to which the driving voltage whose phase is shifted by 180 degrees with respect to the upper electrode 216 is applied.
The upper electrode 218 is formed from the same material as the upper electrode 216. The upper electrode 218 is electrically coupled to the pad 205 via the wiring 209. The voltage is applied to the second piezoelectric actuator 208 such that the second piezoelectric actuator 208 is displaced in a second direction opposite to the first direction (for example, the second direction corresponds to the expansion direction if the first direction corresponds to the contraction direction).
With this arrangement, since the second support part Z2 can be bent in the direction opposite to the direction in which the first support part Z1 is bent, the bending amount of the support body 212 can be increased.
The wiring 209 is provided on an upper surface of a part of the common lower electrode 206 which is located in the first support part Z1. The wiring 209 includes a piezoelectric body 221 which is formed on the common lower electrode 206 and is formed from the piezoelectric material as is the case with the piezoelectric body 215; and a wiring body 223 formed from the same material as the upper electrodes 216 and 218. The wiring body 223 has an end portion coupled to the pad 205 and another end portion coupled to the upper electrode 218. The piezoelectric body 221 is deformed in the second direction when the voltage is applied to the second piezoelectric actuator 208.
It is noted that the first piezoelectric actuator 207, the second piezoelectric actuator 208 and the wiring 209 are formed by successively forming on the common lower electrode 206 a piezoelectric film (for example, a PZT (zircon acid lead titanium) film) as a base material for the piezoelectric bodies 215 and 221 and a metal layer (for example, Ti/Pt multilayered film formed by multilayering a Ti film and a Pt film) as a base material for the upper electrodes 207 and 208, and then patterning the piezoelectric film and the metal film by etching (see Patent Document 1, for example).
[Patent Document 1] Japanese Laid-open Patent Publication No. 2008-35600